The Last Of Us: Inspiration Behind the Infected

Main protagonist, Joel, fights off some Infected.
Main protagonist, Joel, fights off some Infected.

The Last Of Us, released in 2013 by Naughty Dog, was met with critical and fan acclaim, and many believe that it is on its way to become a classic. The game is applauded for its simple yet effective narrative direction, as well as gameplay mechanics. The game follows a tried and true formula: surviving an undead apocalypse. Zombies have dominated the video game industry for years, from Resident Evil to Dead Island,and these creatures have been imagined in a variety of forms and with different names. However, a common consensus is that they represent our inner animalistic nature that has come to life.The usual trope is a virus outbreak that leads to the undead. The Last Of Us breaks the zombie infection mold by presenting a different take on zombies: a fungal infection. The Infected in The Last Of Us behave like the zombies we have come to know, but their appearance and infection inspiration are unique. The infection that devastates the world in The Last Of Us is the Cordyceps Brain Infection, and it is modelled after the real life Cordyceps fungus. The inspiration behind the Infected came to the directors, Bruce Straley and Neil Druckman, after watching a BBC Planet Earth clip.

“Nature is way scarier than anything we could ever imagine.”

The clip from BBC’s Planet Earth showcases the Cordyceps fungus and its infection of an ant. The ant then proceeds to latch onto a tree stem and the fruiting body of the Cordyceps begins to grow out of the ant’s head. The complete growth may take up to three weeks, but once complete the spores will be released, and any ants in the vicinity are likely to become infected and follow the same fate. If an infected ant is discovered, the other ants will dump the infected away from the colony in order to protect the rest of the colony. In an interview with Game Informer 1, the lightbulb of inspiration didn’t turn on right away for Straley and Druckman, but it came at the end when the the narrator, Sir David Attenborough, stated that the more numerous the species, the more likely it was to become infected. “What if this thing jumped to humans?” is the question that Druckman and Straley attempted to answer when they created the Infected.

Cordyceps: attack of the killer fungi - Planet Earth Attenborough BBC wildlife


There are thousands of different species of Cordyceps. Cordyceps are a genus of ascomycete fungi, commonly known as the ‘sac fungi’, and are mostly parasitic on insects and arthropods. They reproduce by releasing ascospores (spores that are not capable of movement on their own), usually held in an ascocarp (the fruiting body that grew out of the ant’s head). Cordyceps are mostly used as medicinal mushrooms. The species most often used for pharmaceutical purposes are Cordyceps militaris and Cordyceps sinensis, which is considered a caterpillar fungi. Medicinal uses of Cordyceps can be dated back hundreds of years according to Chinese and Tibetan medical books. They predominately grow in humid climates. The Cordyceps species shown in the Planet Earth documentary, Ophiocordyceps unilateralis, is a unique species because it can alter the mind of the infected insect. Most Cordyceps do not have that ability and function like regular fungi. The Infected in The Last Of Us, although no specific species was mentioned in the game, appears to be inspired by Ophiocordyceps unilateralis, as well as Cordyceps ignota. 2 3

Ophiocordyceps unilateralis

An ant, infected with Ophiocordyceps unilateralis, sprouting a fruiting body.
An ant, infected with Ophiocordyceps unilateralis, sprouting a fruiting body.

This species of Cordyceps is the major inspiration behind the Infected from The Last Of Us. It is also referred to as the ‘zombie fungus’. The target of O. unilateralis are the carpenter ants that commonly reside in forests. Once the fungus infects the insect it will release chemicals that attack the nervous system of the ant. Once the nervous system is attacked the ant will become a puppet to the fungus. The ant will then be forced to attach itself, via the ‘death grip’, onto a branch of vegetation. This is where the ant will stay until it dies. At this point the ascocarp will grow out of the ant’s head and release spores with the intent to infect other ants. The fungus relies on reproduction through the ants in order to survive. Studies by Charissa de Bekker 4, a molecular biologist at Pennsylvania State University, indicate that the fungus creates different chemicals for different ant species. This suggests that the O. unilaterallis may ‘know’ the brain of its target and can adapt accordingly. Further research is going to look into how this phenomena works, as well as which chemicals are secreted. De Bekker’s studies suggest that guanidinobutyric acid (GBA) and sphingosine are involved in the brain hijacking process. Interestingly enough, these chemicals also appear to play a role in human neurological disorders.

Cordyceps ignota

A tarantula that has been infected by Cordyceps ignota.
A tarantula that has been infected by Cordyceps ignota.

The main target for this species of Cordyceps are tarantulas. The Cordyceps ignota species has elaborate ascocarp growth that produces multiple fruiting bodies. Like Ophiocordyceps unilateralis, Cordyceps ignota will slowly kill its prey and then release spores in order to complete the life cycle. Cordyceps ignota does not zombify the tarantula, it merely kills it. Tarantulas who are infected by Cordyceps ignota create a strikingly beautiful, yet terrifying image.

The Infected

In The Last Of Us the Cordyceps Brain Infection was caused by infected crops from South America. This can be found at the beginning of the game by reading a newspaper in Joel’s house. All the information gathered in game about the infected comes from files found throughout the game. According to a pamphlet found in game, the only way to become infected is by bodily contact with an Infected or by inhaling the spores released by Infected corpses. The same pamphlet also mentions that there is no known cure for the Cordyceps Brain Infection. It also appears that the Center for Disease Control has stopped looking for a cure. However, a militia group, The Fireflies, are still searching for a treatment. Finding a cure has proven difficult because the fungus grows while the host is still alive, effectively slowly ceasing their higher brain function, and within two days the host will enter stage one of the infection.

A Runner still maintains human resemblance.
A Runner still maintains human resemblance.

Stage one of the infection is the weakest stage. The Infected are referred to as Runners. They have poor eyesight; the cordyceps attack the eye area first. However, Runners still have a physical human resemblance and their moans are still human. Their body language is slow, perhaps an indication that they are trying to resist the infection still, but they will attack readily when provoked. Runners, although still human-like, have heightened senses and can more easily detect the player than human AI’s. The Runners are more stylized as a modern interpretation of a zombie as opposed to the Infected caused by the Cordyceps.

It is during the Stalker stage of the infection that pure animalistic instinct takes over.
It is during the Stalker stage of the infection that pure animalistic instinct begins to take over.

Stage two begins shortly after a week from infection and can last up to a year. The Infected in this stage are referred to as Stalkers. During this stage the Infected have the vision and speed of the Runners, but they attack with the fierceness attributed to the stage three infected. Stalkers begin to show proficient fungal growth on the body, most notable around the head. Sometimes this fungal growth appears to be glowing. This glow actually comes from the fungus. Cordyceps are capable of bioluminescence. The fungal growth at this stage will have taken over most of the Infected’s face, leaving only one eye visible. Stalkers are easily recognized by their croaking sounds caused by the fungus advancing in the throat. Stage two is also the stage when the beginnings of echolocation start to take place. Echolocation begins because the Infected are becoming less reliant on the sense of sight since their eyes are practically destroyed entirely by the fungus. Stalkers like to hide and then ambush their victims, exemplifying that the Infected have become more animalistic in nature.

Clickers rely on echolocation in order to find prey.
Clickers rely on echolocation in order to find prey.

The third stage of the infection takes place about a year after initial infection and the Infected are named Clickers; named aptly for the ‘clicking’ sound it makes when using echolocation. At this stage the Infected has had prolonged exposure to the Cordyceps fungus and have virtually no human resemblance except for their body shape. The Clickers, like the Stalkers, can be seen glowing due to bioluminescence.The fungus has completely taken over the head and the Clicker relies solely on echolocation to find its prey. The echolocation is not as sophisticated as the echolocation used by bats, but aligns more with human echolocation used by those who are blind. Bruce Straley mentioned a blind boy who could ride is bike using only echolocation as inspiration. When a Clicker locates the player it will go berserk and attack until you, or it, is dead.

Bloaters are the rarest of all the infected.
Bloaters are the rarest of all the infected.

The fourth and final stage of the infection is the Bloater stage. Not much is known about the Bloater stage because it is rare to encounter a Bloater. It is unknown how long it takes to reach the final stage, but it estimated that it takes at least ten years after the initial infection. A Bloater has a fungal armour surrounding its body, therefore making it hard to pierce and kill. Like Clickers, the Bloaters use echolocation to find its prey, however since the Bloater has a completely deformed face the echolocation is less refined than a Clickers. Bloaters throw Mycotoxin, a common toxin released by various fungi, at the player.

Once an Infected has been killed the fungus will continue to grow, just like real life Cordyceps. It will grow to cover the entire body of the Infected and the fungus will attach the body to any nearby surface. The fungus will then emit spores that will infect anybody in the vicinity. This is why Joel, and other human characters, can be seen wearing face masks throughout the game.

The life cycle of the Infected is quite similar to the life cycle of many Cordyceps fungi. This is especially true regarding the death phase of the fungus. The overall behaviour of the in-game Cordyceps fungus is similar to O. unilaterallis, but the appearance of the Infected more closely resembles Cordyceps ignota.

Could We Become The Infected?

As of right now there is no evidence to suggest there will be a Cordyceps infection that wipes out up to sixty percent of mankind like in The Last Of Us. There is no species of Cordyceps that targets humans, and the fact that many species of Cordyceps are orally taken for medicinal purposes further enhances the fact that Cordyceps are not a real imminent danger for humans. However, that does not mean it couldn’t happen. With any living species there is evolution. In hundreds or thousands of years the Cordyceps fungus could, theoretically, adapt to infect humans. It would take an extensive amount of time since there is no known Cordyceps that infects mammals presently. While it is possible that a Cordyceps infection could, eventually, target humans naturally, it is not thought of as a threat.
The idea of a man made Cordyceps infection is also intriguing. Cordyceps have been studied for medicinal purposes for centuries, but new discoveries involving species like O. unilaterallis have led to more research on the fungi’s freaky infection. It could be possible that future experimentation with the Cordyceps fungus could lead to a man-made bioweapon in the future. Although, this can be said for any fictional infection presented in media. The notion that the Cordyceps fungus could infect humans is one that is distant and, at the moment, is known to be practically non-existent. It is interesting to theorize about though.

Joel and Ellie are the stars of The Last Of Us, but the Infected encountered are stars in their own way. The research behind the Infected is based on something concrete and real, and it leads to a refreshing take on the zombie apocalypse trope. Using a real fungus leads to interest in real science and nature, and that is an accomplishment in its own right.

Works Cited

  1. Game Informer. “The Inspirations for The Last of Us.” Online video clip. Youtube. Youtube, 05 April 2015. Web. 23 July 2015.
  2. “Cordyceps.” Wikipedia: The Free Encyclopedia. Wikimedia Foundation, 28 June 2015. Web. 17 July 2015.
  3. Holliday, John, and Matt Cleaver. “Medicinal Value of the Caterpillar Fungi Species of the Genus Cordyceps (Fr.) Link (Ascomycetes). A Review.” International Journal of Medicinal Mushrooms 10.3 (2008): 219-234. Web.
  4. Castro, Joseph. “Zombie Fungus Enslaves Only Its Favorite Ant Brains.” Live Science. N.p., 09 September 2014. Web. 20 July 2015.

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  1. DClarke

    Great article and very terrifying in a real way! I am not sure that anybody should read this article who wants to sleep at night but it is very well informed and researched.

  2. For too long people have underestimated the artistic merit video games can poses and the level of emotional weight they can carry. I’m not afraid to say one of my single biggest influences on my desire to one day become a writer is this game. The story is absolutely fantastic, the characters and their development cycles are so interesting and thought provoking. When you really dig beneath the surface, this game reveals some harsh truths about human nature, morality and relationships. What a complete and utter privilege it has been playing this game.

    • Lexzie

      I agree 100%. The game, although it follows a familiar trope, is anything but a trope itself.
      I believe it is a must play for any doubters of gaming narratives.

  3. I just finished this last week and I had it originally for PS3… Never finished it and traded it in for this game. It is without a doubt the best game I have ever played. It is a masterpiece of everything this industry is about.

  4. I had the ending ruined for me by a friend. Is it still worth a purchase?

    • Lexzie

      Most defiantly!
      The ending is a masterpiece in its own way, although it cannot be fully appreciated without partaking in the entire journey.
      This game is really about the journey as opposed to the ending. I would recommend a play through even though you know what the ending will be, because you will not be disappointed.

  5. Thank you for this great piece and thank you Naughty Dog.

  6. Whitaker

    I played The Last of Us on both the PlayStation 3 & 4. Both look amazing & the story is just awesome.

  7. Treadway

    The emotions I experienced while playing this game were ridiculous. Fear, anxiety, awe, and a pinch of sadness and anger.

    • Lexzie

      There have only been a few games that have had me experience a spectrum of emotions. This was defiantly one of them.

    • Fortner

      Yes, just going through the journey and playing through it is worth alot more than the ending. Theres a lot more thats gonna happen to you than just the ending. How you get to that end is the most amazing thing. Don’t miss out on it.

  8. Hibbard

    I’m liking a lot about what this game has to offer although the enemy encounters could use some more variety. For such a serious game from a storytelling standpoint the enemies are actually kind of goofy with some really weird animations. Still I’m having a great time.

    • Lexzie

      I would have to agree with you there. I find most zombie animations in games pretty goofy, though.

  9. I simply love this game! Got the PS4 bundle awhile back. Never played it on the PS3. One of my all time favorite games of all time…

  10. TBH I hated the first couple hours of the game but it got dramatically better once Tess died. Once Joel and Ellie start their relationship and journey together everything just clicks. The only thing that I wanted to happen that didn’t is Joel telling Ellie that she is his daughter. After he told her she wasn’t I thought it was happen at the end.

    My favorite parts of the game were the sick sniper part, when you are covering the two black guys and Ellie, and my other favorite is when you are playing as Ellie hunting the Elk and escaping the cannibals town.

    • Lexzie

      I personally adored ghe start of the game. The Winter segment was defiantly the high point for me as well.

  11. Derrick

    I like the depth you’ve gone in this article.

  12. I was really interested in TLoU at first, hoping for a gritty character study. The relationship between Joel and Ellie was something I was looking forward to learning more about, especially after Naughty Dog revealed they were not related.

    But the introduction of zombies totally killed it for me. And then seeing the circumstances bringing the two together was just Hollywood-cliche material…

    As well, as more ‘gamey’ aspects (levelling up, Listen Mode, HUD interface) were revealed, they seemed to be antithetical to the realism Naughty Dog first proposed.

    • Lexzie

      You can defiantly tell that the game was inspired by the Hollywood version of The Road for sure.

    • I’m loving the game. I don’t see how you could think the infected ruined the game considering the infection is the entire reason why the world went to crap. To remove them is to remove the entire premise of the game.

      What other reason for a post apocalyptic world would you have preferred? Aliens? Zombies from the grave? World War 3? I actually found the infected people with the fungus growing on them to be very original. The concept of seeing spores in the air to let you know you’re about to be in deep crap was genius IMO.

      Sure, the humans end up being the bigger threat which is basically how every infection story turns out. But the reason for that situation to begin with is because of the infection.

    • Well they’re not zombies, they’re infected humans. So there are some distinctions there, to a degree.

      Honestly, the Infected are not the main threat in the game, so I don’t really think they hurt it at all.

  13. The problem with the zombie genre attempting to be scientific is that it still uses the “undead” element from the original voodoo-based zombies. It doesn’t matter if a virus or mold or fungus is the cause of “zombieism”, the host body still ends up being dead. A virus can’t reanimate dead tissue. This particular take is no different. The ant dies. The spider dies. The fungus doesn’t then take over and make the spider or ant walk around and eat things. I want to see a zombie movie or video game where there is no “undead” element. The virus or fungus can infect the brain, make the host do things, but the body remains alive. That fixes a lot of the logic issues with the genre.

    • Lexzie

      I think that would improve the genre as well, but the undead theme is so engraved unto society now it may be hard the break.

  14. LimeWhitten

    Completed this 4 times now. Looking to play again in about 6 months. The games that damn good.

  15. The only thing I was disappointed about with this game was how the multiplayer suffered. It was unpolished, but well balanced in the early version. I found the newest iteration to have a lot of connection issues along with way overpowered guns. I have played through the story more times than I can count and can honestly say it satisfies every time.

  16. I beat the game this evening, and honestly this is one of the best games I’ve played in a long time. I really enjoyed the character development between Joel and Ellie, and it was amazing seeing how their relationship develops throughout the game. Beyond the character development, the environments that Naughty Dog created were extraordinary.

    The world was very diverse, and I enjoyed the locations they selected. Furthermore, I felt like they did a great job with the art direction as I have always imagined nature slowly taking back the world over time after the apocalypse. Finally the combat was solid, and I like how they had an emphasize on survival with limit supplies and resources. You really had to resort to stealth kills, or finding a way around the enemy, or carefully time your shots. I like how you had many choices to approach the enemies, and your approach varies from the infected to humans.

  17. Best game I’ve ever played since Half-Life 2.

  18. Hands down, probably best adventure/action game I’ve ever played. Game is long, makes you connect to characters and so thrilling!

  19. lincoln

    Really makes you want a new Jak game…

    • Lexzie

      Funny enough, when Neil and Bruce were first brainstorming ideas for a new game they considered a new Jak game, but ultimately, after watching the BBC clip, decided on an apocalyptic story.

  20. I liked the crafting, I think it made it more realistic.

  21. Damn nature, you scary! Great article.

  22. Just finished The Last of Us the other day. Greatest thing to ever happen to the PS3. Love when developers do their homework!

  23. Shizuko

    I just got this game w/ my PS4. I’m looking forward to playing this for the 1st time.

  24. This game immersed me so deeply. I couldn’t stop playing it. I would always tell myself, “okay, after this part you gotta go to bed.”, but I would end up just playing the game still. Best game I’ve played since the PS1 and PS2 days.

  25. top game, best i have ever played

  26. RobbyIvey

    When i first started playing It looked great but I just didn’t get into it. Put it in a few months later and started playing and wow! Incredible game! When you get into the story it really takes off. Great story and really enjoyed it.

  27. This game on grounded though. I love this masterpiece

  28. Demetrius

    This game is a great game and answer to the whole tired “zombie” thing. It’s also the best video game I have ever played. The story, acting, and character development is more real and engaging than almost every movie or book.

  29. Nicole Williams

    There have been so many different takes on the “zombie apocalypse” theme in movies, books, games, etc. Many of them are ambiguous when it comes to explaining how the epidemic started, so it’s refreshing to read about one that’s grounded in some sort of reality.

    Great article!

  30. Although the linear story hurt its replay value as a game, The Last of Us presented a very engaging apocalyptic storyline. For me, it effectively created an emotional connection to the characters which is an absolute must in any type of survival narrative.

  31. Awesome article, its nourishing to see the kind of research put into this game.

  32. I’m a couple hours into this and I’m really not enjoying it. Several times I’ve had Runners turn around and attack me when I’m crouched and sneaking up behind them. The AI feels really buggy and unpredictable and the movement of the whole thing feels heavy and very clumsy.

    • Lexzie

      It’s a shame you aren’t enjoying the game. I really enjoyed it and it is one of my favourite games now. I agree though, there are some gameplay flaws, but none happened to me that deterred my enjoyment.
      I hope you found the science behind the Infected interesting though 🙂

  33. I really liked the DLC.

  34. Still have yet to play this masterpiece and I have no idea why.

  35. Still trekking through the campaign on my PS4. I agree with most on here that it brings out emotions that most games don’t. I have found that I genuinely care what happens to the characters. At same time, and I saw this was mentioned above, the infected take away the seriousness in a way. They’re goofy looking and don’t always deliver that “Holy crap, I’m too scared to continue” feeling.

  36. jambles

    I have recently started playing this game, and it is awesome! It’s beautiful, intriguing, and challenging! I’m not sure how many times I’ve died because I wasn’t careful. In terms of the infected, I think it is a brilliant take on the zombie genre–incorporating nature as an aspect instead of a virus brought about by science. Great article.

  37. My only issue with the infected is that the earlier stages seem a bit too much like generic zombies. When later stages are so cool and unique, why do the earlier ones have to seem quite so much like other stuff we’ve seen before?

  38. Christina Airola

    This is an interesting article, and definitely educational. I think it’s easy to overlook the fact that the infected in TLOU are more than just derivatives of the zombie trope, probably simply because we’ve become so accustomed to zombie fiction and all that it entails. The fact that this particular infection spread from a real fungal infection is actually quite scary.

    This is why I love Naughty Dog. They always produce phenomenal games and put 150% effort into their work.

  39. It’s been a while since I’ve seen this game, but this article has rekindled my interest. Maybe I’ll pick up a copy and give it a go.

  40. Great article, good job

  41. Can’t wait for the sequel

  42. There are so many ways the human race could be turned into “infected”. I definitely think The Last of Us took the best approach because it turned out to be a masterpiece. I’d love to see more games utilizing different types of world ending infections.

  43. I know a few people who looked over this game when it was released and re-released for the PS4 because they thought it was just another zombie game. It was so hard to try and convince them that is was so. much. more. And they’re not wrong, there is an over-saturation of zombie content in games lately but there is a reason we keep returning to that monster. Never in the game are the infected referred to as zombies but honestly, we were all thinking it when we first played it. By the end of the game, I was so immersed in the world that to me, they weren’t zombies and I could only see them as infected. I think that was a good sign that the story telling was just top notch.

  44. I just finished the Last of Us and I sorely regret not playing it sooner. Perhaps these mutinous spores represents Mother Nature’s wrath for our grievances. The story itself represents how Karma can come around and get at you in the worst possible way.

  45. I love that the infection is based on something in real life, it adds to the creepy factor of the zombies. The small bit of realism makes players stop and think about what would happen if humans ever became infected.

  46. GiovanniZeko

    The reason behind the infected in the Last of Us is what really got me into the game. It was just a you and some friends against hordes of zombies, it was survival with a real story. Ellie and Joel didn’t just run around trigger happy killing all of the zombies in their path. You needed strategy and to prepare for each fight. Also the chemistry between Joel and Ellie really brought me into the game even more, plus the beautiful visuals. Naughty Dog once again bringing a masterpiece to gamer’s around the world.

  47. I love this game with all of my heart, and it bonded my brother and I really well through mutually being so terrified and excited about the game.

    I had no idea how real the inspiration for the infected was, and as a fairly new video game lover, that makes me appreciate video games so much more.

    Thank you!

  48. Emily Deibler

    I recall learning about the Cordyceps in my high school biology class and wondering what would happen if such a thing could mutate and infect humans. Good to know the idea was utilized in a stellar game.

  49. Last of us is spectacular. never played it though.

  50. Tofuboy

    Realistically speaking, the global mutation featured in the game is probably the most plausible events that can happen to us in terms of pandemic in video game. I’ve played the game multiple times since its first release on the PS3 and it is one of the best gaming experience I’ve had for a long time. Just hope the fungus that inspired the concept behind this game would eventually evolve into affected humans. It is terrifying just to imagine.

  51. Wonderful Article! I’ll admit, I got the goosebumps while reading this.

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